World War II Searchlight BatteryAccessories and how they allworked together!

An Anti-Aircraft Searchlight Battery was used for
the
detection, location and illumination of enemy aircraft during darkness
enabling Gun Batteries to fire at enemy aircraft efficiently. The
battery was made up of 2 transport trucks, Searchlight, Control
Station,
Sound Locator, Power plant, and interconnecting cables.

Acoustic location was used from mid-WW1 to the early years of WW2
for
the passive detection of aircraft by picking up the noise of the
engines.
It was rendered obsolete before and during WW2 by the introduction of
radar,
which was far more effective.Before Radar, the Sound Locator was the first practical means of
detecting enemy airplanes at a distance in the night sky by listening
to
their engines with the aid of listening sound horns. The size of the
horns
served to gather in and acoustically amplify more of the sound, and
thus
increased the range of detection. The spacing of the horns aided the
operator's
binaural sense in determining the plane's direction.Below is a photo of one of the last Sound Locator unit that was
used during World War II, Model M-1, made by Sperry Corp. The azimuth
operator
listened to the left and right horn for direction information, and the
elevation operator listened to the top and bottom horns for elevation
information.
There was also the Acoustic Correction Operator to compensate for sound
delay. As the operators pointed this large hearing device, their
direction and elevation movement would generate electric signals
that would be sent to the searchlight control station, or to the
searchlight directly, using a selsyn system. During the
start
of the war, radar was invented and during the war eventually replaced
these
sound locators to detect aircraft. When replaced by radar, Sound
Locators were then placed in the field as decoys to let the enemy think
sound locators were still being used instead of radar.Sound locators were built by the Sperry Corp. Sperry's wartime
contribution
was significant. By1943, the company was manufacturing 300 different
products
for the war effort, two-thirds of which had been developed within the
prior
ten years. The sound locator picks up approaching planes before
they
are visible and determines their exact position, speed, and direction
of
flight. Simultaneously, the anti-aircraft director, functioning as a
computing
mechanism, determines the direction, elevation, and setting required to
aim the anti-aircraft gun at the approaching airplane and transmits
this
information automatically to the guns through a remote control system.Not only did Sperry invent and manufacture these products during
the six-year period from 1939 to 1945, Sperry also ran in-house schools
where they housed, fed, and trained over 77,000 military and naval
personnel
in the use and maintenance of Sperry equipment.

1941 Sperry Searchlight and Model M1 Sound Locator

Note the very large hoses going to the operators
head.
The sound was not electrically amplified to the operator, but
acoustically
coupled to the operators ears using hoses like the stethoscope a doctor
uses to listen to your heart.

Below are early 1927-1935-model sound locators .
They
had 4 horns. One operator listened to the left and right
horn
for direction information, and the other operator listened to the top
and
bottom horns for elevation information. These units were used
since
the early 20's

Below are Sound Locators used by other Countries

Japan
England
Germany

France

Other Locating Devices that were used in place of
the Sound Locator in aiming the Searchlight

Heat Detecting Locator

Heat detectors were used to locate enemy aircraft. Looking like a
searchlight,
this device swept the sky to detect heat from the engines of enemy
aircraft.
Thermopiles and control equipment designed by the Signal Corps
Laboratories
were mounted in a mechanical structure previously built by the
General
Electric Company on an Engineer Contract. As operated in 1937, the
heat
detector received directional data from the radio equipment and
in
turn controlled the pointing of a searchlight.

Radar Locator

As the war, and technology progressed, the new invention of
Radar
was added to the list of Locator devices used to point the Searchlight
to light up enemy aircraft targets. It was Radar that eventually
made the searchlight battery obsolete in tracking enemy aircraft.

Searchlight Control Station

Once enemy aircraft was located by the Sound Locator, the Control
Station was used to aim the searchlight visually by remote control. The
control station was placed several hundred feet away the searchlight in
order to see illuminated aircraft better. The beam was so bright,
if you were right next to the searchlight, you would mostly see
illuminated
atmosphere in the path of the beam. This distance was also
for safety. You do not want to be next to a searchlight pointed into
the
sky full of enemy aircraft as these lights also make great targets.

Electric signals from the Sound locator was sent to the
Searchlight
control station using a selsyn type system to send control signals to
the
zero locator meters that were on top of the station. Two of
the operators, looking at zero locator meters, one for direction and
one
for elevation, would watch these meters and keep the meters on a zero
reading
using hand cranks on the side of the unit. Keeping these meters set at
zero would keep the control station and searchlight in sync with
the same direction and elevation as the locator device tracked enemy
aircraft.The Commander was the third man on this station, and wass
the observer. With the observers head in a harness, and using
binoculars
attached to the station, as the station was aimed by the other two men
following the zero locator meters, the observer was forced to visually
look at the same direction and elevation that the locators were aimed
at.
Once the observer was able to spot the enemy aircraft, he would then
take
full control of the station using the crank controls located in front
of
him. These controls were directly connected to the same crank controls
the two other operators used to aim the station. Using the
control
station, he would now send Selsyn signals to the searchlight so it
would
track the observers actions. The observer could also throw a
switch
on the control station so the searchlight could take Selsyn control
signal
directly from the locator device whether it be a sound, heat, or radar
locator.

The Searchlight

Finally, the signals from the control station or sound locator are
sent
to the searchlight. Here, the searchlight operator maintains the light
mechanism. He assures that the carbons are burning correctly, the beam
is focused, and is the one who throws the switch to start the arc
burning
on command given by the control station Commander..In the event of a communication failure, he may also control the
aim of the light by hand control. This is done by using a long,
10
foot rod with a wheel on the end. With this rod he can walk the
searchlight
in the direction he wants and turn the wheel to the elevation he wants.
The 10 foot distance give him a better view of the object away from the
beam path.

After the War

After W.W. II, Radar had taken over the job the searchlight once had
in spotting and tracking enemy planes. The military kept some
units
that were used as spotlights through the Korean War, but most of the
lights
were scrapped and sold to the public to be used for the next 60 years
as
searchlights in the outdoor advertising industry for the promotion of
Grand
Openings, sales, and special events..